Process for coating recessed surface areas



Nov. 20, 1.962 w. c. BORNEMANN 3,065,100

PROCESS FOR COATING RECESSED SURFACE AREAS Original Filed Feb. 13, 1961 .FIGS 5 INVENTOR.

ZVZ' Z Z am 6.,50222622202221 I; filaim. (Ci. 117-37) The present invention pertains to coating apparatus. More particularly it has to do with the method for coating recessed surface areas such as indicia cast in a preferably transparent plate. The apparatus disclosed for demonstrating the method herein disclosed is covered in my patent issued of even date herewith.

The present application is a division of my copending application U.S. Serial No. 88,853, filed February 13, 1961.

lndicia bearing displays such as signs, instrument panels and the intelligence media may be formed by casting or incising the indicia into a surface in reverse or mirror image. The recessed areas are then coated with a material, such as paint, to provide the necessary contrast to set out the configuration of the indicia so that they may be readily observed from the opposite side of the plate. One use of presentations of this sort for an example is for dial plates in radios and the like. Often, the indicia is cut into a sheet of transparent material such as lucite. Upon illumination of the plate into which the indicia are out either by edge or back lighting, the painted recessed portions stand out vividly.

One prior method of applying a coating to the recessed areas is to spray or otherwise cover the entire surface of the plate with material and then to wipe ad the excess, leaving the coating only within the recesses. Such a technique is most wasteful of time and of the coating material. Another approach has been to carefully paint the coating material into the recesses with a brush. This is exceedingly costly in time, especially when done by hand.

It is accordingly a general object of the present invention to provide a method for coating recessed areas of the kind described and yet which avoids the aforenoted disadvantages.

Another object of the present invention is to provide a method for coating areas recessed into a plate automatically and with a minimum of time and eifort.

Still another object of the present invention is to provide a method of the class described capable of rapidly coating the recesses with a minimum of waste, either as to eifort or material.

An apparatus for illustrating the process invention herein claimed includes a table upon which the recessed plate is disposed for controlled vibration. Overlying the table is a housing, and a plurality of tubes that communicate with and project downwardly therefrom with the tubes being disposed in a configuration corresponding to that of the recessed areas in the plate. A reservoir of coating material is included within the housing. Freely slidable within each tube is a needle having its lower end projecting below the tube and its upper end closingly engageable with the upper end of the tube. The housing is lowered to press the needle lower ends against the recessed areas and displace the needle upper ends from engagement with the tubes, permitting the coating material to flow evenly and gently into the recessed areas.

The features of the invention which are believed to be new are set forth with particularity in the appended claim. The invention, together with further objects and advantages thereof, may best be understood however, by reference to the following description taken in conjunction with the accompanying drawings, in which:

Patented Nov. 20, 1962 FIG. 1 is a perspective view, partially in cross-section, showing apparatus embodying the present invention;

FIG. 2 is a fragmentary cross-sectional view taken along the lines 2-2 in FIG. 1;

FIG. 3 is a fragmentary perspective view of a portion of a plate bearing indicia-representing recessed areas;

FIG. 4 is a fragmentary cross-sectional end View of the apparatus shown in FIG. 1; and

FIG. 5 is a schematic diagram depicting the wave shape of a vibration imparted to the apparatus shown in FIGS. 1, 2 and 4.

The present invention pertains to a process for coating, with a material such as paint, recessed areas 10 formed in a surface of a plate 11 (FIG. 3). For example, as to one area of utility, by filling recessed area 10 with an opaque paint and forming plate 11 from a translucent or transparent material such as lucite, back lighting of the latter causes the coated recessed area to, stand out with a high degree of visibility. Dial plates of radio apparatus commonly incorporate indicia means of this kind.

As illustrated for purposes of explaining the present invention, the apparatus includes a table 12 upon which the plate 11 is disposed for coating of its recessed areas. Overlying table 12 is an enclosure 13'. Enclosure 13 is supported upon posts 14 projecting upwardly from table 12 and enabling movement of the enclosure toward and away from the table. Downward movement of enclosure 13' is limited by an upwardly projecting stop 12 threaded through table 12.

Secured within the lower portions of enclosure 13' is a first dispenser housing 13. Projecting downwardly from housing 13 and communicating with the interior thereof are a plurality of tubes 15 arranged in a configuration corresponding to recessed areas 18 and in plate 11. For a given application, at least one such tube 15 preferably is disposed in alignment with each linear portion of the indicia character formed in plate 11.

Freely slidable within tubes 15 are respective needles 16, the lower ends 17 of which project beyond the lower ends of tube 15. Preferably, the lower end portion of the tubes are bent inwardly toward but spaced from needles 16. The upper end of each of needles in is flared to form a valve member 16a closingly engageable with the correspondingly flared inner side walls of tubes 15.

The interior of housing 13, about needles 16, constitutes a reservoir 18 for the coating medium, in this instance an opaque or semi-opaque paint having a consistency preferably between that of a paste and that of water. Upon lowering of enclosure 13 and hence of housing 13 toward plate 12, the lower end of needles 16 engage the bottom of recessed areas it} whereupon 1e needles are moved upwardly relative to tube 15. In consequence, the coating material is permitted to flow downwardly from reservoir 13 through the tube and gently into recessed areas 10. Upon subsequent raising of housing 13, the upper end of needle 16 closes with that of tube 15 and thereby inhibits further disposition of the coating material.

More precise control of needles and of the disposition of the coating material is insured by including elements within housing 13 to maintain even and proper distribution of the coating material into all of the tubes. To this end, immediately overlying the upper ends of needles 16 is a layer 19 of elastomer material impervious to the coating medium but perforated at 1% for the downward flow of paint. A thin layer of perforated elastomer is suitable to rest upon the valve member 16:: to cause closing movement thereof. Immediately above material layer 19 is a layer 29 of resilient matter such as felt which is likewise pervious to and is adsorbtive of the coating medium. Added eveness of coating material diss3 tribution is attained by the disposition over layer 26 of a plurality of small lead shot 21, or other suitable weights to help in the operation of the valve member 16a.

In order tordeposit a plurality of different colored coating mediums respectively to different ones of the re cessed areas a tandum arrangement is provided in which a second housing 25 is disposed above housing 13 and is similarly constructed insofar as it includes a reservoir for the coating medium together with layers 19 and 2% corresponding to layers 19 and 20 and weights 21 corresponding to weights 2.1, all as previously described. Tubes 15', enclosing needles 16, project downwardly from housing 25 through housing 13. Tubes 15 are otherwise similar to tubes 15 and are arranged in a desired configuration with respect to a portion of the recessed areas 1th in plate ll.

Introduction of the coating materials into housings 13 and 25 is accommodated byaccess openings 27 and 28, respectively. One color of coating medium may be insorted into one reservoir and a different colored coating medium inserted into the other.

Movement of housings 13 and Z5 downwardly toward plate 12 positions the lower ends of tubes 15 and 15' immediately above recessed areas 10. At the same time, the lower ends of needles In and 16 engage the recessed areas whereupon the needles are forced upwardly to dis engage their upper ends from those of tubes 15 and 15'. Thereupon, a passage is opened beneath layers 19 and 19 permitting'the coating mediums to flow downwardly through tubes '15 and 15' and into recessed areas 10. Upon subsequent raising of housings l3 and 25, needles to and 16 .are urged downwardly and into sealing engagement at the upper ends of tubes 15 and 15, terminating the flow of coating medium through the tubes.

Increased assurance of opening and closing the needle valve members Ida and against undesired splattering of plate 11 is enjoyed by placing housings l3 .and Z5 alternately under pressure and vacuum. To this end, the reservoir area of each housing communicates with a pressure control unit 3% coupled through a conduit 31 to a source of compressed air and through a conduit 32 to a vacuum pump. In a conventional manner, control unit is synchronized, through a micro-switch system (not shown), to admit pressure within the coating medium reservoirs upon downward positioning of housings l3 and 25. Similarly, upon the subsequent raising of housings 13 and 25, the reservoirs are placed in communication with conduit 32; the resultant vacuum within the reservoirs tends to draw the coating medium upwardly within tubes 15 and 15 thereby positively inhibting further discharge.

In order to obtain both uniform and complete coating of the entire surface area of recessed areas 10, the plate 11 and bed 12 preferably. are subjected to vibration. To this end, transducer units 33 .and 34 are secured respectively on the bed 12 near the side and the end wall respectively, although the bed 12 is made of light material such as aluminum, it is preferred that the transducers be supported on the bed and operate directly in the plate 11. Upon lowering of housings 13 and 25 to a position at which needles16 and 16' engage recessed areas 10, transducers 33 and 34 are energized through micro-switches on their undersides to vibrate plate 11 in two horizontal directions. Vibration is terminated upon withdrawal of tubes 16 and 16 from their lowered position, the vibration preferably being maintained for a short duration following removal of the needles from contact with the recessed areas. Most advantageous coating is obtainable by vibrating the plate 11 with a clipped sine-wave motion as represented in FIG. 5. More particularly, such motion is clipped on one-half cycle of the housing movement as indicated by the wave form shown in FIG. 5. Abrupt clipping of the housing movement is readily attainable by placing a stop in the path of the movement of thetransduced element or within the transducers 33 and 34. Thus, the paint which contacts the plate 11 in the grooves it), acquires momentum with the plate during the sine-wave portion of the motion and this momentum causes the paint to flow and spread in the grooves to points remote from the needle when the sine-wave motion of the plate is clipped as Where the plate is abruptly stopped. The vibrations otherwise are rapid and of short excursion, the frequency being variably adjusted for optimum results during operation in view of ditferent weights of plates which will be processed.

It is also to be noted that this vibration is effective upon the needles contacting the plate and shakes the needle to assist in the paint fiow therethrough, which, along with the vertical movement of the needle in the ports, keeps the flow path open for the paint to flow when free to do so. This vibration can be done by band also but there should be for best results a repeated sudden stopping of the plate after movement of the paint with the plate has been instituted. However, the transducers may need only strike the plate sharply after being stationery momentarily and similar results will be performed provided the plate is returned to the starting position by a spring or by a second blow made sharply after the plate has come to rest following the first blow.

As herein modified, a multiplicity of colors of coating material may be dispensed. It will be readily understood that still further dispensing units may be disposed in tandum with the two described in order to increase the number of colors affixed in a single operation.

The process described above is capable of dispensing a coating material such as paint into indicia representing recesses While so dispensing only the exact amount of paint required and thereby avoiding wastage. In addition, the dispensed coating medium is caused to fiow evenly over the entire recessed area yet the apparatus is long enduring.

Thus needles of common size and flow characteristics may be employed with recesses of any width, the vibration of the plate in the direction of the greatest width; of the indicia recesses being adjusted whether in frequency or amplitude or both, to provide a faster spread in that direction, the two transducers working independently of each other.

While a particular embodiment of the present invention has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects. Accordingly, the aim in the appended claim is to cover all such changes and modifications as fall within the true spirit and scope of the in' vention.

What is claimed is:

Themethod of coating the surfaces of indicia recessed in the surface of a plate comprising depositing particles ofpaint in said indicia and holding said paint in said recessed indicia under the influence of gravity, establishing a common inertia between the paint particles and plate, abruptly overcoming the inertia of the plate thus established, and simultaneously momentarily continuing the inertia of the paint thus established to spread the paint particles over the sides of the recessed indicia against the influence of gravity.

References Cited in the file of this patent UNITED STATES PATENTS 

